The subject of the present invention is a method of obtaining fibrous carbon materials by carbonization of cellulosic fibrous materials carried out continuously or batchwise in the presence of at least one organosilicon compound. Characteristically, said organosilicon compound is chosen from the family of crosslinked, cyclic or branched oligomers and resins, which have a number-average molecular mass of between 500 and 10 000 and which consist of units of formula SiO.sub.4 (called Q.sub.4 units) and units of formula SiO.sub.xR.sub.y (OR').sub.z.